Harmen Beurmanjer

78 Chapter 6 Abstract Background: Gamma-hydroxybutyrate (GHB) dependence is associated with a severe, potentially lethal, withdrawal syndrome and relapse rates as high as 60% within three months of detoxification. Baclofen has been shown to decrease self-administration of GHB in mice and reduce relapse in a case series of GHB-dependent patients. Controlled studies on the effectiveness of baclofen to prevent relapse in GHB-dependent patients are lacking. Aim: To assess effectiveness of baclofen in preventing relapse in GHB-dependent patients. Methods: An out-patient multicentre, open-label, non-randomized, controlled trial in GHB-dependent patients (n=107) in the Netherlands. Treatment as usual (TAU: n=70) was compared with TAU plus baclofen 45-60mg for three months (n=37). Outcome measures were rates of lapse (any use) and relapse (using GHB on average once a week or more during), based on self-report. Side effects were monitored with a baclofen side effects questionnaire. Treatment groups were compared using chi-square analyses, with both per protocol (PP) and intention to treat (ITT) analyses. Results: GHB-dependent patients treated with baclofen after detoxification showed no reduced lapse rates, but reduced relapse and dropout rates, compared to patients receiving TAU only (24% versus 50%). While both ITT and PP analyses revealed similar results, the effectiveness of baclofen prescribed per protocol was slightly higher than in ITT analysis. Conclusions: This study showed potential effectiveness of baclofen in preventing relapse in patients with GHB dependence after detoxification. Though promising, future studies with longer follow-up and a randomized double-blind design should confirm these findings before recommendations for clinical practice can be made.